Legendary hedge fund investor Jeremy Grantham says there is no doubt that solar and wind energy will “completely replace” coal and gas across the globe, it is just a matter of when.

The founder of $100 billion funds manager GMO Capital is known as a contrarian. But he suggests that the pace of change in the fuel supply will surprise everyone, and have huge implications for fossil fuel investments.

“I have become increasingly impressed with the potential for a revolution in energy, which will make it extremely unlikely that a lack of energy will be the issue that brings us to our knees,” Grantham writes in his latest quarterly newsletter.

“Even in the expected event that there are no important breakthroughs in the cost of nuclear power, the potential for alternative energy sources, mainly solar and wind power, to completely replace coal and gas for utility generation globally is, I think, certain.

“The question is only whether it takes 30 years or 70 years. That we will replace oil for land transportation with electricity or fuel cells derived indirectly from electricity is also certain, and there, perhaps, the timing question is whether this will take 20 or 40 years.”

Grantham’s predictions go against the conventional wisdowm of the fossil fuel industry, but they the thoughts of many people, including Stanford researcher Tony Seba, who said last year this could occur within a few decades.

And Grantham says it could happen quicker than even he believes, and will have major implications for new investments in the fossil fuel industry – a topic very much in mind for project developers and bankers in Australia.

“I have felt for some time that new investments today in coal and tar sands are highly likely to become stranded assets, and everything I have seen, in the last year particularly, increases my confidence,” Grantham writes.

“China especially is escalating rapidly in its drive to limit future pollution from coal and gasoline and diesel powered vehicles. Increased smog last year in major cities led to an unprecedented level of general complaint.

“China simply can’t afford to have Chinese and foreign business leaders leaving important industrial areas in order to protect the health of themselves and their families. Nor are they likely to be comfortable with a high level of sustained complaint from the general public. They have responded in what I consider to be Chinese style, with a growing list of new targets for reducing pollution. A typical example recently was an increase of 60% in their target for total installed solar by the end of 2015! Hardly a month goes by without a new step being announced.”

He also questioned whether th $650 billion spent by the fossil fuel industry searching for new oil reserves was a smart idea, given his recent experience of a colleague’s Tesla. Grantham, the former onwer of a 12-year-old Volvo, described his journey from New York to Boston as his best ever car experience, and suggested that the slump in battery costs would mean the $75,000 vehicle like Teslas would soon be available at $40,000.

“One can easily see that in 10 years there could be a new world order in cars. (And if that weren’t enough, there is a wholly different attack on the traditional gasoline engine from an entirely new technology, the hydrogen fuel cell, to be introduced by Toyota this year.)

In short, with slower global economic growth, more fuel-efficient gasoline and diesel vehicles, more hybrids, cheaper electric cars, more natural gas vehicles, and possibly new technologies using fuel cells and, conceivably, methanol, it is certain that oil demand from developed countries will decline, probably faster than expected.

“Some emerging countries, notably China, are likely to take more dramatic and faster steps to reduce demand than we have ever thought about. Already they have 200 million electric vehicles – mostly motorbikes – almost as many as the rest of the world squared.

“Total global oil demand at current prices or higher is likely to peak in 10 years or so. At much lower prices we would fairly quickly lose most of our high-cost production: deep offshore, fracking, and tar sands.

“Times may be changing faster than we think. My guess is that oil prices will be higher than now in 10 years, but after that, who knows?

“The idea of “peak oil demand” as opposed to peak oil supply has gone, in my opinion, from being a joke to an idea worth beginning to think about in a single year. Some changes seem to be always around the corner and then at long last they move faster than you expected and you are caught flat-footed.”

A minor correction Giles, if I may. In your earlier piece on Tony Seba of Stanford, I believe you had written that his forecast was that fossils will be all but gone by 2030, 16 years from now. I still have the article on file.